I would never skip HS. We easily spend a full day there. We look at it as an opportunity to really enjoy the day without rushing around to get everything done. Some of our favorite rides are Tower of Terror and Rockin Roller Coaster. We like to sit and eat dinner at Brown Derby or Mama Melrose. We don't feel rushed to leave the restaurant either, which is nice. We like to end the day at Fantasmic. The show after the park closes is a bonus. Plus we like riding Tower of Terror at night, and walking around each park at night. You can't do that if you park hop.
We are actually spending two full days at HS this trip, but we do go to the parks for ten days. I would say it depends on how many days you will be at the parks. We need at least two days at MK. (We actually do three.) We do 3 at MK, 3 at AK, 2 at EP, and 2 at HS. We usually do 3 at EP and 2 at AK, but now with Pandora we switched it this year.